Silymarin is the active ingredient in the hard fruit of the milk thistle plant Silybum marianum.
Milk thistle has been used for thousands of years to treat a variety of ailments, particularly disorders of the liver.
Silymarin exhibits anti-oxidant properties and has been found effective for protecting the liver from some forms of environmental damage and toxins.
Traditionally, silymarin was extracted from the seeds of the milk thistle plant, but today it is also available as a synthesized product composed of several flavonolignans.
Silymarin from milk thistle is usually standardized at 80 percent concentration in supplements, though some suppliers may provide lower or higher concentrations.



- Supports liver health & detox
- Anti-oxidant & anti-inflammatory properties
- Improves insulin sensitivity & cholesterol
Silymarin from Milk Thistle Seeds
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Silymarin is a flavonoid complex comprised of several flavonolignans and flavonoids, including: silibinin (which is thought to be the most active ingredient of silymarin); silydianin; and silychristin.
One of the main therapeutic features of silymarin is its apparent ability to protect the liver from toxic substances.
For example, one of the earliest recorded uses of milk thistle occurred in Ancient Greece when the plant was used to treat an individual who had consumed a poisonous mushroom.
Silymarin has been used to protect the liver in rare cases of poisoning caused by the consumption of death cap mushrooms (Amanita phalloides).
A dose of 20-50 milligrams per kilogram of silibinin (a component of silymarin composed of silybin A and silybin B) in 500 millilitres of 5 percent dextrose solution has been injected into the vein every six hours for 24 hours as a treatment for death cap mushroom poisoning.
Silibinin is thought to prevent the uptake of amatoxins by liver cells, thus protecting undamaged liver tissue. However, there is still insufficient evidence to definitively support this use and silibinin is not readily available in the United States.
Milk Thistle Extracts, on the other hand, are readily available and do not require a prescription because they are classified as natural health supplements.
Silymarin Health Benefits
Silymarin from milk thistle has historically been used to treat a variety of ailments and is still used for a number of indications. Silymarin has been observed to lower LDL cholesterol and blood sugar in diabetics.
Further, there is some evidence that it can help control the size of fat cells and is sometimes used for weight control in conjunction with a sensible diet plan and exercise.
Silymarin is used in combination with complementary herbs to treat the hot flashes and night sweats associated with menopause. It is also thought to support digestive health and has been observed to reduce dyspepsia (heartburn), GERDS and IBS symptoms.
Antioxidant Properties of Milk Thistle Extract
A number of Milk Thitle and silymarin’s purported health benefits are associated with the compound’s antioxidant properties. Silymarin is composed of flavonolignans and flavonoids, which are known antioxidants. Antioxidants neutralize free radicals that can otherwise damage and kill healthy cells.
Further, silymarin has been observed to increase the level of the antioxidant enzyme superoxide dismutase (SOD) in cell cultures. Increasing antioxidant content helps ward off damage caused by free radicals, which is increasingly connected to the development of disease and effects of aging.
Silymarin for Liver Protection
The antioxidant effect of silymarin is only one way it helps protect the liver. Milk Thistle extract is widely recommended by naturopathic doctors to promote liver health and detoxification of the body.
Silymarin also regulates the intracellular content of glutathione and increases the level in the liver, which can improve the efficiency of the detoxification process. Silymarin is thought to act as a cell membrane stabilizer and permeability regulator. This is what prevents hepatotoxic (toxic to liver) substances from entering the hepatocytes (liver cells).
Milk thistle seed supplements may also promote the regeneration of liver cells. Silymarin facilitates ribosomal RNA synthesis, which stimulates liver regeneration.
It also inhibits the transformation of stellate hepatocytes into myofibroblasts. This is the process where collagen fibres are deposited on the liver, which can lead to cirrhosis. It helps stimulate protein synthesis in the liver. This increases the production of new liver cells to replace damaged cells.
In clinical trials silymarin has been observed to protect liver function in individuals with acute viral hepatitis, toxic hepatitis and alcohol-related liver disease (including cirrhosis). Trial subjects received 140 mg silymarin three times a day for 41 months.
During the four-year trial, 58 percent of the individuals who received daily doses of silymarin survived versus only 39 percent in the placebo group.
Anti-Inflammatory Properties of Silymarin
Silymarin inhibits the synthesis of leukotrienes, which cause inflammation in a number of respiratory conditions, including asthma and aspirin-exacerbated respiratory disease (AERD). The symptoms associated with these conditions include airflow obstruction, increased secretion of mucus, mucosal accumulation, and bronchoconstriction.
Silymarin also inhibits the inflammation caused by leukotrienes in allergic rhinitis (hay fever) and psoriasis. It is used as an anti-inflammatory to relieve pain in arthritis and rheumatism.
Silymarin is being studied for its anti-tumor properties and is thought to be an angiogenesis inhibitor (a compound that stops the formation of blood vessels that feed tumors) and may protect the liver during chemotherapy treatment. A study published in Cell Biology International in August 2008 showed that silymarin may inhibit metastasis in prostate cancer.
It has also been studied for its use with chemotherapy agents, doxorubicin and cisplatin, as an adjunct to prevent or reduce chemotherapy-induced toxicity. Silymarin is the main active ingredient in Leviaderm® cream used by breast cancer patients to reduce radiation treatment skin damage.
Is Silymarin from Milk Thistle Extract Safe?
Silymarin is generally well tolerated as an oral supplement. Those allergic to ragweed or the members of the Asteracea Compositae plant family should avoid this supplement. Silymarin from milk thistle may act as a mild laxative. It may also cause bloating, diarrhea, gas, indigestion, loss of appetite and nausea.
This supplement should be used with caution if you are pregnant or breast feeding. Milk thistle may lower blood sugar and should be used with caution by those with diabetes or low blood sugar.
Do not take this supplement if you have breast, uterine or ovarian cancer or endometriosis or uterine fibroids. It should also not be taken with medications that break down or change in the liver. Do not take it with anti-seizure medication Phenytoin (Dilantin) or statins.
As with all supplements, be sure to speak with your doctor before you start to take silymarin extract from milk thistle seeds.
- Rotem C, Kaplan B. Phyto-Female Complex for the relief of hot flushes, night sweats and quality of sleep: randomized, controlled, double-blind pilot study. Gynecol Endocrinol 2007;23:117-22
- Ross SM. Milk thistle (Silybum marianum): an ancient botanical medicine for modern times. Holist Nurs Pract. 2008 Sep-Oct;22(5):299-300.
- Saller, R, Meier, R, Brignoli, R. The Use of Silymarin in the Treatment of Liver Diseases. Drugs. 2001;61(14):2035-63.
Article last updated on: April 29th, 2018 by Nootriment